Morphogenetic, Metabolic and Molecular Dynamics during Mycelial Interactions among Fungal species
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Date
2021
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Publisher
AAU, Jorhat
Abstract
In nature, microorganisms interact/compete with one other for food and
space and the type of interactions are unique to each interacting species. Fungal-fungal
interactions are complex, and different types of secondary metabolites are secreted
during interaction. In this study, 14 fungal isolates were facilitated in 105 possible
combinations to interact in potato dextrose agar (PDA). Ten interactions between
different fungal isolates showed mutual replacement with each fungus; capturing
territory from the other. Thirty-five interactions showed complete replacement as
growth of one of the fungal partners was inhibited. In forty-six interactions, formation
of barrage was observed leading to deadlock type of interaction wherein both fungi have
restricted growth.
The barrage formation during interaction was further studied with two
fungal interactions viz., (i) T. coccinea vs. L. lactinea and (ii) T. coccinea vs.
T. versicolor. Microscopic changes were observed in the hyphal growth during
interaction like hyphal coiling, dense mycelial network, pore formation. Fungal-fungal
interaction often leads to the change in metabolite profile of both the interacting fungus
which may have potential implication in industry or agriculture. The metabolites
produced during interaction of Trametes coccinea (F3) with Leiotrametes lactinea (F9)
and Trametes coccinea (F3) with Trametes versicolor (F1) was analysed through Liquid
Chromatography coupled with Mass Spectroscopy (LC-MS). Most of the metabolites
secreted during interaction are associated with defensive response. The bipartite fungal
interaction resulted in the production of a dark brown colour pigment – melanin as
confirmed by the LC-MS, FTIR and NMR analysis. Moreover, the fungal-fungal
interaction also led to increase in the production of laccase, a group of multicopper
oxidases involved in detoxification of toxic compounds. Further increased activity of
superoxide dismutase, an enzyme that catalyzes the dismutation of the superoxide anion
to hydrogen peroxide was also recorded during fungal–fungal interaction. There was
significant increase in the activities of hydrolytic enzymes including cellulase, xylanase
and chitinase during in vitro fungal-fungal interaction, suggesting the importance of
such interactions for commercial enzyme production. Quantitative real-time PCR
revealed upregulation of lcc1 (encoding a laccase enzyme) and few other stress related
genes of T. versicolor during its hyphal interaction with T. coccinea, suggesting a direct
correlation between laccase production and melanin production. The study helped to
gain a better understanding on the morpho-physiological, biochemical and gene
expression profiles during in vitro fungal-fungal interaction. Such interactions induce
the production and secretion of an array of metabolites and enzymes which can be
prospected towards biotechnological applications.